Lubricant oil additive compositions

ABSTRACT

A lubricant oil composition having a synergistic oxidative stability is disclosed, the composition comprising at least one hindered phenolic antioxidant, at least one mono-boronated hindered phenolic antioxidant, at least one di-boronated hindered phenolic antioxidant, at least one alkylated diphenylamine and at least one organomolybdenum compound. The invention also provides a lubricating oil additive concentrate composition that imparts synergistic oxidative stability to a lubricant oil upon its addition, the concentrate composition comprising at least one hindered phenolic antioxidant, at least one mono-boronated hindered phenolic antioxidant, at least one di-boronated hindered phenolic antioxidant, at least one alkylated diphenylamine and at least one organomolybdenum compound. Further, the concentrate compositions of the present invention may also be prepared with a high concentration of hindered phenolic antioxidants without deleterious effects on viscosity or lubricant solubility.

FIELD OF THE INVENTION

The invention relates to lubricant oil additive compositions andlubricating oil compositions containing the same. More particularly,this invention relates to combinations of hindered phenolicantioxidants, boronated hindered phenolic antioxidants, alkylateddiphenylamines and organomolybdenum compounds useful as lubricant oilcompositions and lubricating oil additive compositions.

DESCRIPTION OF RELATED ART

Hindered phenolic and boronated hindered phenolics are well known in theart, including large molecular phenolics incorporating the moiety,2,6-di-tert-butylphenol, and the like. See, for example, the followingUS and foreign patents: U.S. Pat. No. 4,927,553; U.S. Pat. No.3,356,707; U.S. Pat. No. 3,509,054; U.S. Pat. No. 3,347,793; U.S. Pat.No. 3,014,061; U.S. Pat. No. 3,359,298; U.S. Pat. No. 2,813,830; U.S.Pat. No. 2,462,616; GB 864,840; U.S. Pat. No. 5,698,499; U.S. Pat. No.5,252,237; US RE 32,295; U.S. Pat. No. 4,547,302; U.S. Pat. No.3,211,652; and U.S. Pat. No. 2,807,653

The use of alkylated diphenylamine as an antioxidant additive inlubricating oil formulations is also well known in the art. See, forexample, the following US patents: U.S. Pat. No. 5,620,948; U.S. Pat.No. 5,595,964; U.S. Pat. No. 5,569,644; U.S. Pat. No. 4,857,214; U.S.Pat. No. 4,455,243; and U.S. Pat. No. 5,759,965.

There are many examples in the patent literature showing the use ofmolybdenum additives as antioxidants, deposit control additives,anti-wear additives and friction modifiers. See, for example, thefollowing US and foreign patents: U.S. Pat. No. 5,840,672; U.S. Pat. No.5,814,587; U.S. Pat. No. 4,529,526; WO 95/07966; U.S. Pat. No.5,650,381; U.S. Pat. No. 4,812,246; U.S. Pat. No. 5,458,807; WO95/07964; U.S. Pat. No. 5,880,073; U.S. Pat. No. 5,658,862; U.S. Pat.No. 5,696,065; WO 95/07963; U.S. Pat. No. 5,665,684; U.S. Pat. No.4,360,438; U.S. Pat. No. 5,736,491; WO 95/27022; U.S. Pat. No.5,786,307; U.S. Pat. No. 4,501,678; U.S. Pat. No. 5,688,748; EP 0 447916 A1; U.S. Pat. No. 5,807,813; U.S. Pat. No. 4,692,256; U.S. Pat. No.5,605,880; WO 95/07962; U.S. Pat. No. 5,837,657; U.S. Pat. No.4,832,867; U.S. Pat. No. 4,705,641; EP 0 768 366 A1; U.S. Pat. No.6,103,674; U.S. Pat. No. 6,010,987; U.S. Pat. No. 6,110,878; EP 1 136496 A1; U.S. Pat. No. 6,150,309; U.S. Pat. No. 6,232,276; U.S. Pat. No.6,306,802; EP 1 136 497 A1; U.S. Pat. No. 5,888,945; U.S. Pat. No.6,187,723; U.S. Pat. No. 6,117,826; U.S. Pat. No. 6,103,674; U.S. Pat.No. 6,063,741; U.S. Pat. No. 6,017,858; U.S. Pat. No. 5,994,277; andU.S. Pat. No. 6,174,842.

SUMMARY OF THE INVENTION

The present invention generally provides a lubricant oil compositionhaving improved oxidative stability, the composition comprising at leastone hindered phenolic antioxidant, at least one mono-boronated hinderedphenolic antioxidant, at least one di-boronated hindered phenolicantioxidant, at least one alkylated diphenylamine, and at least oneorganomolybdenum compound. The invention also provides a lubricating oiladditive concentrate composition that imparts synergistic oxidativestability to a lubricant oil upon its addition, the concentratecomposition comprising at least one hindered phenolic antioxidant, atleast one mono-boronated hindered phenolic antioxidant, at least onedi-boronated hindered phenolic antioxidant, at least one alkylateddiphenylamine, and at least one organomolybdenum compound. Further, theconcentrate compositions of the present invention may also be preparedwith a high concentration of hindered phenolic antioxidants withoutdeleterious effects on viscosity or lubricant solubility.

The synergistic improvement of oxidative stability in lubricant oilcompositions and lubricating oil additive concentrate compositionscomprising at least one hindered phenolic antioxidant, at least onemono-boronated hindered phenolic antioxidant, at least one di-boronatedhindered phenolic antioxidant, and at least one alkylated diphenylamineis disclosed in concurrently filed, commonly owned U.S. ProvisionalApplication 60/758,754 filed on Jan. 13, 2006, and in PCT applicationnumber PCT/US2007/060489 that claims priority to U.S. ProvisionalApplication 60/758,754, both of which are hereby incorporated byreference in their entirety to the extent allowed by applicable law. Thepresent invention improves upon the disclosure of U.S. ProvisionalApplication 60/758,754 such that lubricant oil compositions andlubricating oil additive concentrate compositions comprising at leastone hindered phenolic antioxidant, at least one mono-boronated hinderedphenolic antioxidant, at least one di-boronated hindered phenolicantioxidant, at least one alkylated diphenylamine, and at least oneorganomolybdenum compound exhibits improved oxidative stability comparedto conventional formulations.

In one aspect, a lubricant oil or lubricating oil additive concentratecomposition comprising: (a) 4,4′-methylenebis(2,6-di-tert-butylphenol),(b) 4,4′-methylenebis(2,6-di-tert-butylphenol)-mono-(di-alkylorthoborate), (c)4,4′-methylenebis(2,6-di-tert-butylphenol)-di-(di-alkyl orthoborate),(d) an alkylated diphenylamine, and (e) an organomolybdenum compound, isan effective antioxidant combination for use in lubricants.

In another aspect, a lubricant oil or lubricating oil additiveconcentrate composition comprising: (a) a hindered phenolic antioxidant,(b) either a single or multiple ortho-borate ester, or combinationsthereof, derived from a hindered phenolic antioxidant, wherein the boronis attached to the hindered phenolic oxygen, (c) an alkylateddiphenylamine, and (d) an organomolybdenum compound, is an effectiveantioxidant combination for use in lubricants.

BRIEF DESCRIPTION OF THE FIGURE

FIG. 1 shows graphical results from Example A.

DETAILED DESCRIPTION OF THE INVENTION

Hindered phenolics suitable for use in the compositions of the presentinvention include phenolics incorporating the 2,6-di-tert-butylphenolmoiety. A suitable hindered phenolic, which is commercially sold byAlbemarle Corporation™ under the trade name Ethanox® 702, is4,4′methylenebis(2,6-di-tert-butylphenol), hereinafter referred to asMBDTBP, having the structure of Structure I below:

Other suitable hindered phenolics include, 2,4-di-tert-butylphenol,2,6-di-tert-butylphenol, 6-tert-butyl-ortho-cresol,2,6-di-isopropylphenol, 2,4-di-sec-butylphenol, higher molecular weighthindered phenolic antioxidants derived synthetically from2,4-di-tert-butylphenol, 2,6-di-tert-butylphenol,6-tert-butyl-ortho-cresol, 2,6-di-isopropylphenol, or2,4-di-sec-butylphenol, butylated hydroxy toluene (BHT), and the like.

The amount of hindered phenolic present in the compositions of theinvention ranges from about 1 to about 50 weight percent of the totalconcentration of hindered phenolic, boronated hindered phenolic, andalkylated diphenylamine. In additional aspects the amount of hinderedphenolic present in the compositions of the invention ranges from about1 to about 40 weight percent, about 1 to about 30 weight percent, about1 to about 25 weight percent, about 1 to about 20 weight percent, andabout 1 to about 15 weight percent of the total concentration ofhindered phenolic, boronated hindered phenolic, and alkylateddiphenylamine.

The mono- and di-boronated hindered phenolics suitable for use in thecompositions of the present invention are derived from the hinderedphenolics described above by reaction with tri-alkyl orthoborates. Onesuch process is disclosed in U.S. Pat. No. 4,927,553. In one aspect,suitable mono- and di-boronated hindered phenolics have the structuresof Structures II and III below:

wherein R₁, R₂, R₃, and R₄ are independently selected from the groupconsisting of linear, branched and cyclic C₁ to C₈ alkyl groups.Examples of such groups include, but are not limited to, methyl, ethyl,n-propyl, iso-propyl, n-butyl, sec-butyl, iso-butyl, n-pentyl,2-methylbutyl, 3-methylbutyl, 2-methyl-2-butyl, 3-methyl-2-butyl,isopentyl, n-hexyl, cyclopentyl, cyclohexyl, 2-ethylbutyl,2-methylpentyl, 3-methylpentyl, 4-methylpentyl, 3-methyl-2-pentyl,4-methyl-2 pentyl, 3-methyl-3-pentyl, 3,3-dimethylbutyl,3,3-dimethyl-2-butyl, 2,3-dimethyl-2-butyl, 2-methyl-2-hexyl,2,2-dimethyl-3-pentyl, 2-heptyl, 3-heptyl, 2-methyl-3-hexyl,3-ethyl-3-pentyl, 2,3-dimethyl-3-pentyl, 2,4-dimethyl-3-pentyl,5-methyl-2-hexyl, 4,4-dimethyl-2-pentyl, 5-methylhexyl, n-heptyl,n-octyl, iso-octyl, 2-ethylhexyl, 2-propylpentyl, 2-octyl, 3-octyl,2,44-trimethylpentyl, 4-methyl-3-heptyl and 6-methyl-2-heptyl.

Other mono- and di-boronated hindered phenolics may be derived fromreacting the specific hindered phenolics described above, or mixtures ofhindered phenolics, with tri-alkyl orthoborates.

The combined total of mono- and di-boronated hindered phenolics presentin the compositions of the invention ranges from about 10 to about 80weight percent of the total concentration of hindered phenolic,boronated hindered phenolic, and alkylated diphenylamine. The ratio ofmono-boronated hindered phenolic to di-boronated hindered phenolic mayvary from about 0.01:1 to about 1:0.01. The amount of mono-boronatedhindered phenolic can be approximately equal to or greater than that ofdi-boronated hindered phenolic.

The amount of MBDTBP in conventional lubricant oil additive concentratecompositions has been limited by its solubility to about 10 wt % of thetotal additive concentrate. However, the present invention provides amethod for increasing the concentration of hindered phenolic antioxidantin the lubricant oil additive concentrate composition to be increased toas high as about 50 wt % by including boronated hindered phenolicantioxidants in the lubricant oil additive concentrate composition.

The alkylated diphenylamines suitable for use in the compositions of thepresent invention are prepared from diphenylamine by reaction witholefins. One particularly useful method of preparing alkylateddiphenylamines is described in US Patent Publication US-2006-0276677-A1(which related to U.S. Ser. No. 11/442,856 filed 30 May 2006, whichclaims priority to U.S. Provisional Patent Application 60/687,182 filedon Jun. 2, 2005 and to U.S. Provisional Patent Application 60/717,322filed on Sep. 14, 2005), which US Patent Publication is incorporated inits entirety by reference herein to the extent allowed by applicablelaw. Both mono- and di-alkylated diphenylamines may be employed, eitheralone are in combination, and have the structures shown in Structures IVand V below:

wherein R₁, R₂ and R₃ are independently selected from the groupconsisting of linear, branched and cyclic C₄ to C₃₂ alkyl groups.Examples of such groups include, but are not limited to, alkyl groupsderived from linear alpha-olefins, isomerized alpha-olefins polymerizedalpha-olefins, low molecular weight oligomers of propylene, and lowmolecular weight oligomers of isobutylene. Specific examples include butare not limited to butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl,undecyl, dodecyl, tridecyl, tetradecyl, dipropyl, tripropyl,tetrapropyl, pentapropyl, hexapropyl, heptapropyl, octapropyl,diisobutyl, triisobutyl, tetraisobutyl, pentaisobutyl, hexaisobutyl, andheptaisobutyl.

The combined total of mono- and di-alkylated diphenylamine present inthe compositions of the invention ranges from about 10 to about 80weight percent of the total concentration of hindered phenolic,boronated hindered phenolic, and alkylated diphenylamine. The ratio ofmono- to di-alkylated diphenylamine may vary from about 0.01:1 to about1:0.01.

Examples of suitable alkylated diphenylamines are nonylateddiphenylamines (NDPA), octylated diphenylamines, mixedoctylated/styrenated diphenylamines (such as Durad® AX55), and mixedbutylated/octylated diphenylamines (such as Vanlube® 961). Further, thenitrogen content of the alkylated diphenylamines can be in the range ofabout 2.0 to about 6.0 wt. %. Lower levels of nitrogen dilute theeffectiveness of the alkylated diphenylamines while higher levels ofnitrogen may adversely impact compatibility of the alkylateddiphenylamines in the lubricant or the lubricant's volatility. Thealkylated diphenylamines can be a liquid or low melting solid.

Organomolybdenum compounds suitable for use in the present inventioninclude sulfur-free compounds, phosphorus-free compounds, andsulfur-containing compounds. The molybdenum content of organomolybdenumcompounds may vary from about 1 wt % to about 15 wt %. The concentrationof the organomolybdenum compound may range from about 1 wt % to about 40wt % of the total concentration of hindered phenolic, boronated hinderedphenolic, alkylated diphenylamine and organomolybdenum compound.

The amount of organomolybdenum compound used in compositions of thepresent invention is such that the weight ratio of molybdenum to boronranges from about 0.01:1 to about 10:1. The molybdenum content of alubricant oil can range from between about 50 to about 1000 ppm and theboron content can range between about 50 to about 500 ppm. Themolybdenum content of a lubricant oil can range from between about 100to about 400 ppm and the boron content can range between about 100 toabout 400 ppm.

Sulfur- and phosphorus-free organomolybdenum compounds may be preparedby reacting a sulfur and phosphorus-free molybdenum source with anorganic compound containing amino and/or alcohol groups. Examples ofsulfur- and phosphorus-free molybdenum sources include molybdenumtrioxide, ammonium molybdate, sodium molybdate and potassium molybdate.The amino groups may be monoamines, diamines, or polyamines. The alcoholgroups may be mono-substituted alcohols, diols or bis-alcohols, orpolyalcohols. As an example, the reaction of diamines with fatty oilsproduces a product containing both amino and alcohol groups that canreact with the sulfur- and phosphorus-free molybdenum source.

Examples of sulfur- and phosphorus-free organomolybdenum compoundssuitable for use in the present invention include the following:compounds prepared by reacting certain basic nitrogen compounds with amolybdenum source as defined in U.S. Pat. Nos. 4,259,195 and 4,261,843;compounds prepared by reacting a hydrocarbyl substituted hydroxyalkylated amine with a molybdenum source as defined in U.S. Pat. No.4,164,473; compounds prepared by reacting a phenol aldehyde condensationproduct, a mono-alkylated alkylene diamine, and a molybdenum source asdefined in U.S. Pat. No. 4,266,945; compounds prepared by reacting afatty oil, diethanolamine, and a molybdenum source as defined in U.S.Pat. No. 4,889,647; compounds prepared by reacting a fatty oil or acidwith 2-(2-aminoethyl)aminoethanol, and a molybdenum source as defined inU.S. Pat. No. 5,137,647; compounds prepared by reacting a secondaryamine with a molybdenum source as defined in U.S. Pat. No. 4,692,256;compounds prepared by reacting a diol, diamino, or amino-alcoholcompound with a molybdenum source as defined in U.S. Pat. No. 5,412,130;compounds prepared by reacting a fatty oil, mono-alkylated alkylenediamine, and a molybdenum source as defined in European PatentApplication EP 1 136 496 A1; and compounds prepared by reacting a fattyacid, mono-alkylated alkylene diamine, glycerides, and a molybdenumsource as defined in European Patent Application EP 1 136 497 A1.

Examples of commercial sulfur- and phosphorus-free oil solublemolybdenum compounds are Sakura-Lube 700 from Asahi Denka, and Molyvan856B and Molyvan 855 from R. T. Vanderbilt Company, Inc.

Molybdenum compounds prepared by reacting a fatty oil, diethanolamine,and a molybdenum source as defined in U.S. Pat. No. 4,889,647 aresometimes illustrated as having one or both of the following structures,

wherein R is a fatty alkyl chain. The exact chemical structure of thesematerials is not fully known and may in fact be multi-component mixturesof many organomolybdenum compounds.

Sulfur-containing organomolybdenum compounds may be prepared by avariety of methods. One method involves reacting a sulfur andphosphorus-free molybdenum source with an amino group and one or moresulfur sources. Sulfur sources include carbon disulfide, hydrogensulfide, sodium sulfide and elemental sulfur. Alternatively, thesulfur-containing molybdenum compound may be prepared by reacting asulfur containing molybdenum source with an amino group or thiuram groupand optionally a second sulfur source. Examples of sulfur- andphosphorus-free molybdenum sources include molybdenum trioxide, ammoniummolybdate, sodium molybdate, potassium molybdate and molybdenum halides.The amino groups may be monoamines, diamines, or polyamines. As anexample, the reaction of molybdenum trioxide with a secondary amine andcarbon disulfide produces molybdenum dithiocarbamates. Alternatively,the reaction of (NH₄)2Mo₃S₁₃.n(H₂O) where n varies between 0 to 2 with atetralkylthiuram disulfide produces a trinuclear sulfur-containingmolybdenum dithiocarbamate.

Examples of sulfur-containing organomolybdenum compounds suitable foruse in the present invention include the following: compounds preparedby reacting molybdenum trioxide with a secondary amine and carbondisulfide as defined in U.S. Pat. Nos. 3,509,051 and 3,356,702;compounds prepared by reacting a sulfur-free molybdenum source with asecondary amine, carbon disulfide, and an additional sulfur source asdefined in U.S. Pat. No. 4,098,705; compounds prepared by reacting amolybdenum halide with a secondary amine and carbon disulfide as definedin U.S. Pat. No. 4,178,258; compounds prepared by reacting a molybdenumsource with a basic nitrogen compound and a sulfur source as defined inU.S. Pat. Nos. 4,263,152, 4,265,773, 4,272,387, 4,285,822, 4,369,119,and 4,395,343; compounds prepared by reacting ammoniumtetrathiomolybdate with a basic nitrogen compound as defined in U.S.Pat. No. 4,283,295; compounds prepared by reacting an olefin, sulfur, anamine and a molybdenum source as defined in U.S. Pat. No. 4,362,633;compounds prepared by reacting ammonium tetrathiomolybdate with a basicnitrogen compound and an organic sulfur source as defined in U.S. Pat.No. 4,402,840; compounds prepared by reacting a phenolic compound, anamine and a molybdenum source with a sulfur source as defined in U.S.Pat. No. 4,466,901; compounds prepared by reacting a triglyceride, abasic nitrogen compound, a molybdenum source, and a sulfur source asdefined in U.S. Pat. No. 4,765,918; compounds prepared by reactingalkali metal alkylthioxanthate salts with molybdenum halides as definedin U.S. Pat. No. 4,966,719; compounds prepared by reacting atetralkylthiuram disulfide with molybdenum hexacarbonyl as defined inU.S. Pat. No. 4,978,464; compounds prepared by reacting an alkyldixanthogen with molybdenum hexacarbonyl as defined in U.S. Pat. No.4,990,271; compounds prepared by reacting alkali metal alkylxanthatesalts with dimolybdenum tetra-acetate as defined in U.S. Pat. No.4,995,996; compounds prepared by reacting (NH₄)2Mo₃S₁₃.2(H₂O) with analkali metal dialkyldithiocarbamate or tetralkyl thiuram disulfide asdefine in U.S. Pat. No. 6,232,276; compounds prepared by reacting anester or acid with a diamine, a molybdenum source and carbon disulfideas defined in U.S. Pat. No. 6,103,674; and compounds prepared byreacting an alkali metal dialkyldithiocarbamate with 3-chloropropionicacid, followed by molybdenum trioxide, as defined in U.S. Pat. No.6,117,826.

Examples of commercial sulfur-containing oil soluble molybdenumcompounds are Sakura-Lube® 100, Sakura-Lube® 155, Sakura-Lube® 165, andSakura-Lube® 180 from Asahi Denka Kogyo K. K., Molyvan® A, Molyvan® 807and Molyvan® 822 from R. T. Vanderbilt Company, and Naugalube® MolyFMfrom Crompton Corporation.

Molybdenum dithiocarbamates are suitable organomolybdenum compounds andhave the following structure:

wherein R is independently selected from hydrogen or an alkyl groupcontaining 4 to 18 carbons, and X is independently selected from oxygenor sulfur.

The lubricating oil may be any basestock or base oil (characterized asGroup I, Group II, Group III, Group IV or Group V as defined by the APIbasestock classification system), or lubricant composed predominately ofaromatics, naphthenics, paraffinics, poly-alpha-olefins and/or syntheticesters. Further, the lubricant may also contain additional additives soas to make the system acceptable for use in a variety of applications.These additives include dispersants, detergents, viscosity indeximprovers, pour point depressants, anti-wear additives, extreme pressureadditives, friction modifiers, corrosion inhibitors, rust inhibitors,emulsifiers, demulsifiers, anti-foaming agents, colorants, seal swellingagents, and additional antioxidants.

The present invention may be useful in passenger car engine oils, heavyduty diesel oils, medium speed diesel oils, railroad oils, marine engineoils, natural gas engine oils, 2-cycle engine oils, steam turbine oils,gas turbine oils, combined cycle turbine oils, R&O oils, industrial gearoils, automotive gear oils, compressor oils, manual transmission fluids,automatic transmission fluids, slideway oils, quench oils, flush oilsand hydraulic fluids. Suitable applications are in engine oils. Asuitable application is in low phosphorus engine oils characterized by aphosphorus content of less than 1000 ppm.

The lubricating oil additive concentrate may or may not contain adiluent oil. If a diluent oil is used, the diluent oil is typicallypresent between 1 and 80 wt. % of the concentrate.

Typically, the total amount of hindered phenolic, boronated hinderedphenolic, alkylated diphenylamine, and organomolybdenum compound thatare added to fully formulated oils depends upon the end use application.For example, in a turbine oil the total amount of hindered phenolic,boronated hindered phenolic, alkylated diphenylamine, andorganomolybdenum compound added to the oil ranges between about 0.05 andabout 1.0 wt. %. In contrast, in an engine oil the total amount ofhindered phenolic, boronated hindered phenolic, alkylated diphenylamineand organomolybdeum compound added to the oil ranges between about 0.2and about 3.0 wt. %. In ultra-low phosphorus engine oils the totalamount of hindered phenolic, boronated hindered phenolic, and alkylateddiphenylamine may approach 5.0 wt. % or more.

An example of a lubricating oil additive concentrate in accordance withthe present invention is as follows:

-   -   (a) 4,4-methylenebis(2,6-di-tert-butylphenol) @ 10 wt. %;    -   (b) 4,4′-methylenebis(2,6-di-tert-butylphenol)        mono-(di-sec-butyl orthoborate) and        4,4′-methylenebis(2,6-di-tert-butylphenol) di-(di-sec-butyl        orthoborate) @ 40 wt. %;    -   (c) dinonyldiphenylamine and monononyldiphenylamine @ 10 wt. %;    -   (d) a molybdenum dithiocarbamate containing 4.5 wt. % molybdenum        @ 20 wt. %; and    -   (e) paraffinic diluent oil @ 20 wt. %.

An example of a low phosphorus engine oil in accordance with the presentinvention is as follows:

-   -   (a) 4,4-methylenebis(2,6-di-tert-butylphenol) @ 0.5 wt. %;    -   (b) 4,4′-methylenebis(2,6-di-tert-butylphenol)        mono-(di-sec-butyl orthoborate) and        4,4′-methylenebis(2,6-di-tert-butylphenol) di-(di-sec-butyl        orthoborate) @ 1.0 wt. %;    -   (c) dinonyldiphenylamine and monononyldiphenylamine @ 0.75 wt.        %;    -   (d) a molybdenum dithiocarbamate containing 4.5 wt. % molybdenum        @ 0.2 wt. %    -   (e) a dispersant concentrate @ 4.8 wt. %;    -   (f) an overbased calcium detergent concentrate @ 1.8 wt. %;    -   (g) a neutral calcium detergent concentrate @ 0.5 wt. %;    -   (h) zinc dialkyldithiophosphate @ 0.6 weight %;    -   (i) a pour point depressant at 0.1 wt. %;    -   (j) a viscosity index improver concentrate @ 8.0 wt. %;    -   (k) an organic friction modifier @ 0.5 wt. %; and    -   (l) paraffinic lubricating oil @ 81.25 wt. %

Example A Oil Thickening and Oxidation at Elevated Temperatures

A passenger car engine oil preblend was prepared in accordance with thepresent invention by blending the following materials:

-   -   (a) 5.000 wt. % of an ashless dispersant;    -   (b) 1.875 wt. % of an overbased detergent containing calcium;    -   (c) 0.521 wt. % of a neutral detergent containing calcium;    -   (d) 0.625 wt. % of a secondary zinc dialkyldithiophosphate; and    -   (e) 91.979 wt. % of a 150N Group II baseoil.        To this engine oil preblend was added the components indicated        in Table 1.

TABLE 1 Components of Examples A.1-A.6. Engine Oil Ex. Example PreblendHPE NDPA BMBDTBP MoDTC G2BO Total No. Type (wt %) (wt %) (wt %) (wt %)(wt %, ppm Mo) (wt %) (wt %) A.1 Comparative 96.00 1.00 0.75 0.4, 2251.85 100.00 A.2 Comparative 96.00 1.25 0.75 0.4, 225 1.60 100.00 A.3Invention 96.00 0.50 1.00 0.4, 225 2.10 100.00 A.4 Invention 96.00 0.751.00 0.4, 225 1.85 100.00 A.5 Invention 96.00 0.75 0.75 0.4, 225 2.10100.00 A.6 Invention 96.00 0.75 1.25 0.4, 225 1.60 100.00 MoDTC =Molybdenum dithiocarbamate containing 4.5 wt. % molybdenum BMBDTBP = asample composed of: 15.6 wt. % 4,4-methylenebis(2,6-di-tert-butylphenol,38.6 wt. % 4,4′-methylenebis(2,6-di-tert-butylphenol)-mono-(di-sec-butylorthoborate), 17.4 wt. %4,4′-methylenebis(2,6-di-tert-butylphenol)-di-(di-sec-butyl orthoborate)(values calculated based upon HPLC analysis), 1.0 wt. % of an ashlessdispersant, and 29.0 wt. % of a 500N naphthenic diluent oil. The samplehas a boron content of 1.23 wt % as determined by ICP. HPE =3,5-di-tert-butyl-4-hydroxyhydrocinnamic acid, C₇-C₉branched alkylesters NDPA = Nonylated diphenylamine G2BO = 150N Group II baseoil

The oxidative stability of these finished engine oils was evaluated in abulk oil oxidation test. Each oil (300 mL) was treated with an ironnaphthenate oxidation catalyst to deliver 110 ppm of iron to thefinished oil. The oils were heated in a block heater at 150° C., while10 liters/hour of dry oxygen was bubbled through the oil. Samples of theoxidized oils were removed at 24, 48, 72, 96, 120, 144, 168 and 192hours. Kinematic viscosities of each sample were determined at 40° C.The percent viscosity increase of the oxidized oil versus the fresh oilwas calculated. The percent viscosity increase results are shown inTable 2.

TABLE 2 Percent viscosity increase of finished oils A.1-A.6 in bulk oiloxidation test. Sample 0 24 48  72 96 120 144 168 192 A.1 0 2.5 3.5 5.133.5 172.4 696.8 (comparative) A.2 0 2.9 4 7.9 100.0 382.1 (comparative)A.3 (invention) 0 0.3 1.3 2.4 3.4 15.4 148.3 716.6 A.4 (invention) 0 0.81.9 2.8 3.3 4.3 6.9 50.6 283.0 A.5 (invention) 0 0.2 1.2 2.1 2.4 3.5 4.713.9 153.8 A.6 (invention) 0 0.9 2.4 3.4 4.4 5.3 8.0 49.4 290.7

A higher percent viscosity increase is a measure of increased oxidationand degradation of the lubricant. These results clearly show that theinventive antioxidant combination in Examples A.3 to A.6 providesuperior oxidation protection compared to the other Examples (A.1-A.2).Antioxidant systems that do not contain the combination of4,4′-methylenebis(2,6-di-tert-butylphenol), boronated4,4′-methylenebis(2,6-di-tert-butylphenol), nonylated diphenylamine andorganomolybdenum compound show poor oxidation control while systemscontaining BMBDTBP, NDPA and MoDTC show superior oxidative control.These results are shown graphically in FIG. 1.

Example B Pressurized Differential Scanning Calorimetry (PDSC)

The oxidative stability of the finished engine oils prepared in ExampleA was evaluated using pressurized differential scanning calorimetryfollowing the ASTM standard test method D 6186 and using the followingoperation conditions: isothermal temperature=180° C., oxygen gas @ 500psig with a flow rate of 100 mL/min, approximately 3 mg sample size,open aluminum pans. Each oil was treated with an iron naphthenateoxidation catalyst to deliver 55 ppm of iron to the finished oil.Oxidation induction times (OIT) were determined according to the ASTMmethod. Each oil was tested in duplicate and the results averaged. TheOIT results are shown in Table 3.

TABLE 3 Oxidation Induction Times in minutes for finished oils A.1-A.6tested using PDSC. Sample ID OIT OIT AVG. A.1 109.48 119.12 114.30 A.2112.33 109.2 110.77 A.3 111.09 113.15 112.12 A.4 156.44 147.78 152.11A.5 143.68 146.24 145.96 A.6 146.67 147.36 147.02

A longer induction time is a measure of increased oxidation stability ofthe lubricant. These results clearly show that the inventive antioxidantcombination in Examples A.4 to A.6 provide superior oxidation protectioncompared to the non-inventive Examples (A.1-A.2). Antioxidant systemsthat do not contain the combination of4,4′-methylenebis(2,6-di-tert-butylphenol), boronated4,4′-methylenebis(2,6-di-tert-butylphenol), nonylated diphenylamine andmolybdenum show poor oxidation control while systems containing BMDTBP,NDPA and MoDTC show superior oxidative control. Also, considerably less,i.e. 25% less, antioxidant is used in inventive oil A.3 versusnon-inventive oil A.2 in order to deliver the same performance level inthe PDSC (112.12 minutes and 110.77 minutes statistically equivalent).

While the compositions and methods of this invention have been describedin terms of preferred embodiments, it will be apparent to those of skillin the art that variations may be applied to the compositions, methodsand/or processes and in the steps or in the sequence of steps of themethods described herein without departing from the concept and scope ofthe invention. More specifically, it will be apparent that certainagents which are both chemically and physiologically related may besubstituted for the agents described herein while the same or similarresults would be achieved. All such similar substitutes andmodifications apparent to those skilled in the art are deemed to bewithin the scope and concept of the invention.

1. A lubricant oil composition comprising at least one hindered phenolicantioxidant, at least one boronated hindered phenolic antioxidant, atleast one alkylated diphenylamine, and at least one organomolybdenumcompound.
 2. The lubricant oil composition of claim 1, wherein the atleast one boronated hindered phenolic antioxidant is derived from the atleast one hindered phenolic antioxidant.
 3. The lubricant oilcomposition of claim 2, wherein the at least one boronated hinderedphenolic antioxidant comprises mono- and di-boronated hindered phenolicantioxidants.
 4. The lubricant oil composition of claim 3, wherein thehindered phenolic antioxidant is4,4′-methylenebis(2,6-di-tert-butylphenol).
 5. The lubricant oilcomposition of claim 4, wherein the mono-boronated hindered phenolicantioxidant has the structure

and the di-boronated hindered phenolic antioxidant has the structure

wherein R₁, R₂, R₃, and R₄ are independently selected from the groupconsisting of linear C₁ to C₈ alkyl groups, branched C₁ to C₈ alkylgroups and cyclic C₃ to C₈ alkyl groups.
 6. The lubricant oilcomposition of claim 5, wherein the at least one alkylated diphenylaminecomprises mono- and di-alkylated diphenylamine.
 7. The lubricant oilcomposition of claim 6, wherein the mono-alkylated diphenylamine has thestructure

and the di-alkylated diphenylamine has the structure

wherein R₁, R₂ and R₃ are independently selected from the groupconsisting of linear, branched and cyclic C₄ to C₃₂ alkyl groups.
 8. Thelubricant oil composition of claim 7, wherein the mono- and di-alkylateddiphenylamine is selected from the group consisting of nonylateddiphenylamines, octylated diphenylamines, mixed octylated/styrenateddiphenylamines, and mixed butylated/octylated diphenyl amines.
 9. Thelubricant oil composition of claim 3, wherein the organomolybdenumcompound is selected from the group consisting of sulfur-freeorganomolybdenum compounds, phosphorus-free organomolybdenum compounds,and sulfur-containing organomolybdenum compounds.
 10. The lubricant oilcomposition of claim 9, wherein the organomolybdenum compound is amolybdenum dithiocarbamate having the structure

wherein R is independently selected from hydrogen or an alkyl groupcontaining 4 to 18 carbons, and X is independently selected from oxygenor sulfur.
 11. The lubricant oil composition of claim 10, wherein theconcentration of the organomolybdenum compound ranges from about 1 wt %to about 40 wt % of the total concentration of hindered phenolic,boronated hindered phenolic, alkylated diphenylamine andorganomolybdenum compound.
 12. The lubricant oil composition of claim11, wherein the weight ratio of molybdenum to boron ranges from about0.01:1 to about 10:1.
 13. The lubricant oil composition of claim 12,wherein the molybdenum content ranges from between about 50 ppm to about1000 ppm and the boron content ranges between about 50 ppm to about 500ppm.
 14. The lubricant oil composition of claim 13, wherein themolybdenum content ranges from between about 100 ppm to about 400 ppmand the boron content ranges between about 100 ppm to about 400 ppm. 15.The lubricant oil composition of claim 4, wherein the concentration of4,4′-methylenebis(2,6-di-tert-butylphenol) is between about 1 to about50 weight percent of the total concentration of hindered phenolic,boronated hindered phenolic, alkylated diphenylamine andorganomolybdenum compound.
 16. The lubricant oil composition of claim15, wherein the concentration of mono- and di-boronated hinderedphenolic is between about 10 to about 80 weight percent of the totalconcentration of hindered phenolic, boronated hindered phenolic,alkylated diphenylamine and organomolybdenum compound.
 17. The lubricantoil composition of claim 16, wherein the ratio of mono-boronatedhindered phenolic to di-boronated hindered phenolic is between about 1:1to about 1:0.01.
 18. The lubricant oil composition of claim 17, whereinthe concentration of alkylated diphenylamine is between about 10 toabout 80 weight percent of the total concentration of hindered phenolic,boronated hindered phenolic, alkylated diphenylamine, andorganomolybdenum compound.
 19. A lubricating oil additive concentratecomposition comprising at least one hindered phenolic antioxidant, atleast one boronated hindered phenolic antioxidant, at least onealkylated diphenylamine, and at least one organomolybdenum compound. 20.The lubricating oil additive concentrate composition of claim 19,wherein the at least one boronated hindered phenolic antioxidant isderived from the at least one hindered phenolic antioxidant.
 21. Thelubricating oil additive concentrate composition of claim 20, whereinthe at least one boronated hindered phenolic antioxidant comprises mono-and di-boronated hindered phenolic antioxidants.
 22. The lubricating oiladditive concentrate composition of claim 21, wherein the hinderedphenolic antioxidant is 4,4′-methylenebis(2,6-di-tert-butylphenol). 23.The lubricating oil additive concentrate composition of claim 22,wherein the mono-boronated hindered phenolic antioxidant has thestructure

and the di-boronated hindered phenolic antioxidant has the structure

wherein R₁, R₂, R₃, and R₄ are independently selected from the groupconsisting of linear C₁ to C₈ alkyl groups, branched C₁ to C₈ alkylgroups and cyclic C₃ to C₈ alkyl groups.
 24. The lubricating oiladditive concentrate composition of claim 23, wherein the at least onealkylated diphenylamine comprises mono- and di-alkylated diphenylamine.25. The lubricating oil additive concentrate composition of claim 24,wherein the mono-alkylated diphenylamine has the structure

and the di-alkylated diphenylamine has the structure

wherein R₁, R₂ and R₃ are independently selected from the groupconsisting of linear, branched and cyclic C₄ to C₃₂ alkyl groups. 26.The lubricating oil additive concentrate composition of claim 25,wherein the mono- and di-alkylated diphenylamine is selected from thegroup consisting of nonylated diphenylamines, octylated diphenylamines,mixed octylated/styrenated diphenylamines, and mixed butylated/octylateddiphenylamines.
 27. The lubricant oil composition of claim 21, whereinthe organomolybdenum compound is selected from the group consisting ofsulfur-free organomolybdenum compounds, phosphorus-free organomolybdenumcompounds, and sulfur-containing organomolybdenum compounds.
 28. Thelubricant oil composition of claim 27, wherein the organomolybdenumcompound is a molybdenum dithiocarbamate having the structure

wherein R is independently selected from hydrogen or an alkyl groupcontaining 4 to 18 carbons, and X is independently selected from oxygenor sulfur.
 29. The lubricant oil composition of claim 28, wherein theconcentration of the organomolybdenum compound ranges from about 1 wt %to about 40 wt % of the total concentration of hindered phenolic,boronated hindered phenolic, alkylated diphenylamine andorganomolybdenum compound.
 30. The lubricating oil additive concentratecomposition of claim 22, wherein the concentration of4,4′-methylenebis(2,6-di-tert-butylphenol) is between about 1 to about50 weight percent of the total concentration of hindered phenolic,boronated hindered phenolic, alkylated diphenylamine andorganomolybdenum compound.
 31. The lubricating oil additive concentratecomposition of claim 30, wherein the concentration of mono- anddi-boronated hindered phenolic is between about 10 to about 80 weightpercent of the total concentration of hindered phenolic, boronatedhindered phenolic, alkylated diphenylamine and organomolybdenumcompound.
 32. The lubricating oil additive concentrate composition ofclaim 31, wherein the ratio of mono-boronated hindered phenolic todi-boronated hindered phenolic is between about 1:1 to about 1:0.01. 33.The lubricating oil additive concentrate composition of claim 32,wherein the concentration of alkylated diphenylamine is between about 10to about 80 weight percent of the total concentration of hinderedphenolic, boronated hindered phenolic, alkylated diphenylamine andorganomolybdenum compound.
 34. The lubricating oil additive concentratecomposition of claim 33, further comprising a diluent oil.
 35. Thelubricating oil additive concentrate composition of claim 34, whereinthe concentration of the diluent oil is between about 1 to about 80 wt%.
 36. An engine oil composition comprising at least one hinderedphenolic antioxidant, at least one boronated hindered phenolicantioxidant, at least one alkylated diphenylamine and at least oneorganomolybdenum compound.
 37. The engine oil composition of claim 36,wherein the hindered phenolic antioxidant is4,4′-methylenebis(2,6-di-tert-butylphenol).
 38. The engine oilcomposition of claim 37, wherein the at least one boronated hinderedphenolic antioxidant comprises a mono-boronated hindered phenolicantioxidant having the structure

and a di-boronated hindered phenolic antioxidant having the structure

wherein R₁, R₂, R₃, and R₄ are independently selected from the groupconsisting of linear C₁ to C₈ alkyl groups, branched C₁ to C₈ alkylgroups and cyclic C₃ to C₈ alkyl groups.
 39. The engine oil compositionof claim 38, wherein the at least one alkylated diphenylamine comprisesa mono-alkylated diphenylamine having the structure

and a di-alkylated diphenylamine having the structure

wherein R₁, R₂ and R₃ are independently selected from the groupconsisting of linear, branched and cyclic C₄ to C₃₂ alkyl groups. 40.The engine oil composition of claim 39, wherein the mono- anddi-alkylated diphenylamine is selected from the group consisting ofnonylated diphenylamines, octylated diphenylamines, mixedoctylated/styrenated diphenylamines, and mixed butylated/octylateddiphenylamines.
 41. The engine oil composition of claim 40, wherein theorganomolybdenum compound is a molybdenum dithiocarbamate having thestructure

wherein R is independently selected from hydrogen or an alkyl groupcontaining 4 to 18 carbons, and X is independently selected from oxygenor sulfur.
 42. The engine oil composition of claim 41, wherein theconcentration of 4,4′-methylenebis(2,6-di-tert-butylphenol) is betweenabout 1 to about 50 weight percent of the total concentration ofhindered phenolic, boronated hindered phenolic, alkylated diphenylamineand organomolybdenum compound, the concentration of mono- anddi-boronated hindered phenolic is between about 10 to about 80 weightpercent of the total concentration of hindered phenolic, boronatedhindered phenolic, alkylated diphenylamine and organomolybdenumcompound, the ratio of mono-boronated hindered phenolic to di-boronatedhindered phenolic is between about 1:1 to about 1:0.01, theconcentration of alkylated diphenylamine is between about 10 to about 80weight percent of the total concentration of hindered phenolic,boronated hindered phenolic, alkylated diphenylamine andorganomolybdenum compound, and the concentration of organomolybdenumcompound is between about 1 to about 40 weight percent of the totalconcentration of hindered phenolic, boronated hindered phenolic,alkylated diphenylamine and organomolybdenum compound.
 43. The engineoil composition of claim 42, wherein the engine oil is used to lubricatean engine selected from the group consisting of a gasoline engine, aheavy duty diesel engine, a natural gas engine, a marine engine and arailroad engine.
 44. An engine oil additive concentrate compositioncomprising at least one hindered phenolic antioxidant, at least oneboronated hindered phenolic antioxidant, at least one alkylateddiphenylamine and at least one organomolybdenum compound.
 45. The engineoil additive concentrate composition of claim 44, wherein the hinderedphenolic antioxidant is 4,4′-methylenebis(2,6-di-tert-butylphenol). 46.The engine oil additive concentrate composition of claim 45, wherein theat least one boronated hindered phenolic antioxidant comprises amono-boronated hindered phenolic antioxidant having the structure

and a di-boronated hindered phenolic antioxidant having the structure

wherein R₁, R₂, R₃, and R₄ are independently selected from the groupconsisting of linear C₁ to C₈ alkyl groups, branched C₁ to C₈ alkylgroups and cyclic C₃ to C₈ alkyl groups.
 47. The engine oil additiveconcentrate composition of claim 46, wherein the at least one alkylateddiphenylamine comprises a mono-alkylated diphenylamine having thestructure

and a di-alkylated diphenylamine having the structure

wherein R₁, R₂ and R₃ are independently selected from the groupconsisting of linear, branched and cyclic C₄ to C₃₂ alkyl groups. 48.The engine oil additive concentrate composition of claim 47, wherein themono- and di-alkylated diphenylamine is selected from the groupconsisting of nonylated diphenylamines, octylated diphenylamines, mixedoctylated/styrenated diphenylamines, and mixed butylated/octylateddiphenylamines.
 49. The engine oil additive concentrate composition ofclaim 48, wherein the organomolybdenum compound is a molybdenumdithiocarbamate having the structure

wherein R is independently selected from hydrogen or an alkyl groupcontaining 4 to 18 carbons, and X is independently selected from oxygenor sulfur.
 50. The engine oil additive concentrate composition of claim49, wherein the concentration of4,4′-methylenebis(2,6-di-tert-butylphenol) is between about 1 to about50 weight percent of the total concentration of hindered phenolic,boronated hindered phenolic, alkylated diphenylamine andorganomolybdenum compound, the concentration of mono- and di-boronatedhindered phenolic is between about 10 to about 80 weight percent of thetotal concentration of hindered phenolic, boronated hindered phenolic,alkylated diphenylamine and organomolybdenum compound, the ratio ofmono-boronated hindered phenolic to di-boronated hindered phenolic isbetween about 1:1 to about 1:0.01, the concentration of alkylateddiphenylamine is between about 10 to about 80 weight percent of thetotal concentration of hindered phenolic, boronated hindered phenolic,alkylated diphenylamine and organomolybdenum compound, and theconcentration of organomolybdenum compound is between about 1 to about40 weight percent of the total concentration of hindered phenolic,boronated hindered phenolic, alkylated diphenylamine andorganomolybdenum compound.
 51. The engine oil additive concentratecomposition of claim 50, wherein the engine oil is used to lubricate anengine selected from the group consisting of a gasoline engine, a heavyduty diesel engine, a natural gas engine, a marine engine and a railroadengine.
 52. A method of increasing the concentration of at least onehindered phenolic antioxidant in a lubricant oil additive concentratecomposition, the method comprising the step of adding at least oneboronated hindered phenolic antioxidant to the lubricant oil additiveconcentrate.